: I have a sump pump with a check valve. My sump pump goes on every 15 minutes and when the cycle is complete I hear a loud slamming noise. Also I have black goop comming out of some of the joints in the plastic pipes? How can I fix these problems?: Thanks for your help.Firsr off loud slamming in check valves is normal.Try to cusion some of the pipes near walls or woodwork,Maybe that will cut down on some of the noise.Black goop!? Sounds like an Amityville movie. I don't know if these are rubber connections or p.v.c. If rubber, tighten the clamps. If p.v.c. the joints may be poorly glued. Probably best to wait till dry season and fix those. Good luck C.